Our principal research objectives are to identify the biochemical and physical structure of the light scattering elements in the cataractous lens and to determine their biochemical origin. We have discovered that Ca ion induces aggregation of calf and human lens crystallins. We have established the presence of a soluble heavy molecular weight (HM) component in human normal and cataractous lenses. The component increases with age and comprises a significant fraction of the nuclear portion of lenses marked by nuclear opacification. Furthermore, the HM fraction from cataractous lenses contains Ca ion. We are presently involved in determining the precise concentration and location of Ca-rich aggregates in cataractous and normal lenses. Additionally, we are investigating techniques to reverse or block Ca-induced aggregation of soluble lens proteins.